The present invention relates generally to a drawout unit, and, more particularly, to a load/line terminal unit configured to make more efficient use of the space within the drawout unit.
In a motor control system, vertical bus bars which carry current to motor controller units are arranged vertically in drawout units. Sliding stabs usually plug into a housing with opposing prongs being biased toward each other on the sliding stabs to contact either side of the bus bars, whereby the electrical connection between the motor controller unit and the bus bars is maintained. Lugs on the sliding stabs are connected to bus straps extending from the lugs to the line side of a circuit interrupting device such as a circuit breaker. Bus straps also extend from the load side of the circuit interrupting device to the line side of a distribution power load circuit, such as a starter.
Load terminals are electrically connected to the load side of the distribution power load circuit and are typically positioned to allow an output cable to be connected to them in a vertical configuration. These load terminals are generally bushings positioned on the bottom of the distribution power load circuit and have an axially threaded terminal to which output cable connections are made. Alternately, output cables of a thinner diameter may have attachments on one end that allow them to be secured to load terminals with screws or bolts. One particular method of securing output cable to a load terminal, as described in U.S. Pat. No. 4,154,993 entitled "Cable Connected Drawout Switchgear", involves mounting circuit equipment on a rolling carriage such that the load terminals engage connectors on stationary cables when the carriage is rolled over the cable connectors. Another method described in U.S. Pat. No. 5,107,396 entitled "Circuit Breaker Combined Terminal Lug and Connector" involves sliding a cable connector disposed axially on the end of a cable into a receiving slot on a terminal lug. Both of these methods of attaching output cable are such that the output cable depends vertically, and not horizontally, from the load terminals.
Output cable extending vertically down from the load terminals must be bent at two right angles thus forming an S-shape before passing through an exit port in the bottom of the drawout unit. Depending on the voltage class, output cable may be up to a few inches in diameter and relatively inflexible due to its construction. Consequently, the minimum bending radius of the cable may be large. Because of this large minimum bending radius of the cable, and because the output port through which the output cable passes is usually not directly below the load terminals, the cable must be bent at right angles twice to pass out of the drawout assembly. Bending the cable to form two right angles requires an appreciable amount of space more than a single right angle bend would require. Thus, the drawout assembly must be of a larger size than is really necessary to accommodate both right angle bends. Furthermore, as the number of output cables depending from the load terminals increases, an increasing amount of space is required at the bottom of the drawout to accommodate the cables.